n/tga - nasa miniature uonitor final report (nasa} 32 p a n92-30381 unclas g3/54 0105114 assessment...
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NASA
Technical
Memorandum
NASA TM- 103587
(NASA-TM-103587) ASSESSMENT OF
HEAD-MOUNTED MINIATURE uONITOR
Final Report (NASA} 32 p
A N92-30381
Unclas
G3/54 0105114
ASSESSMENT OF A HEAD-MOUNTED MINIATURE
MONITOR
Center Director's Discretionary Fund Final Report
(Project Number 89-07)
By J.P. Hale II
Mission Operations Laboratory
Science and Engineering Directorate
June 1992
N/tgANational Aeronautics andSpace Administration
George C. Marshall Space Flight Center
MSFC-Form 3190 (Rev. May 1983)
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I. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED
June 1992 Techn£cal Memorandum5. FUNDING NUMBERS
4. TITLE AND SUBTITLEAssessment of a Head-Mounted Miniature Monitor
Center Director's Discretionary Fund Final ReportfProiect Number 89-07_
6. AUTHOR(S)
J.P. Hale 11
7. PERFORMINGORGANIZATIONNAME(S)AND ADDRESS(ES)
George C. Marshall Space Flight Center
Marshall Space Flight Center, Alabama 35812
9. SPONSORING/MONITORINGAGENCYNAME(S)ANDADDRESS(ES)
National Aeronautics and Space Administration
Washington, DC 20546
8. PERFORMING ORGANIZATIONREPORT NUMBER
10. SPON SORING / MONITORINGAGENCY REPORT NUMBER
NASA TM-I03587
11. SUPPLEMENTARY NOTES
Prepared by Mission Operations Laboratory, Science and Engineering Directorate
12a. DISTRIBUTION/AVAILABILITY STATEMENT
Unclassified-Unlimited
12b. DISTRIBUTION CODE
13. ABSTRACT (Maximum 200 words)
Two experiments were conducted to assess the capabilities and limitations of the Private Eye, a
miniature, head-mounted monitor. The first experiment compared the Private Eye with a CRT and hard
copy in both a constrained and unconstrained work envelope. The task was a simulated maintenance and
assembly task that required frequent reference to the displayed information. A main effect of presentation
media indicated faster placement times using the CRT as compared with hard copy. There were no
significant differences between the Private Eye and either the CRT or hard copy for identification,
placement, or total task times. The goal of the second experiment was to determine the effects of various
local visual parameters on the ability of the user to accurately perceive the information of the Private Eye.
The task was an interactive video game. No significant performance differences were found under either
bright or dark ambient illumination environments nor with either visually simple or complex task
backgrounds. Glare reflected off of the bezel surrounding the monitor did degrade performance. It wasconcluded that this head-mounted, miniature monitor could serve a useful role for in situ operations,
especially in microgravity environments.
14. SUBJECT TERMS
Private Eye, head-mounted display, miniature monitor, light-
emitting diode (LED)
17. SECURITY CLASSIFICATION
iO OF,REPQ RT .nclasslnecl
18. SECURITY CLASSIFICATIONOF THIS PAGE
Unclassified
19. SECURITY CLASSIFICATIONOF ABSTRACT
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15. NUMBER OF PAGES
3916. PRICE CODE
NTIS
20. LIMITATIONOFABSTRACT
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NSN 7540-01-280-5500 Standard Form 298 (Rev 2-89)
ACKNOWLEDGMENTS
This research was supported by a Center Director's Discretionary Fund (No. 89-07) from the
Marshall Space Flight Center. The author would like to thank those who administered these fundsfor the support and resources to condiJct this research. The author also would like to thank Frankie
Rice, a co-op student at MSFC, and Gina Klinzak, of New Technology, Inc., for their help in data
collection in studies 1 and 2, respectively, and Julie Cosper, a co-op student at MSFC, for help in
data collection in study 1 and data reduction and analysis in study 2.
TABLE OF CONTENTS
Page
INTRODUCTION .................................................................................................................... , ........ 1
EXPERIMENT 1............................................................................................................................... 2
Method ................................................................................................................................... 2
Overview ................................................................................................................... 2
Design ........................................................................................................................ 2
Subjects ..................................................................................................................... 2Task ........................................................................................................................... 2
Materials and Apparatus .......................................................................................... 2Procedure ................................................................................................................... 3
Results ................................................................................................................................... 3
Discussion ............................................................................................................................. 9
EXPERIMENT 2 ............................................................................................................................... 10
Method ................................................................................................................................... 10
Overview ................................................................................................................... 10
Design ........................................................................................................................ 10
Subjects ..................................................................................................................... 11Task ........................................................................................................................... 11
Materials and Apparatus ................................. , ........................................................ 11Procedure ................................................................................................................... 12
Results ................................................................................................................................... 12
Discussion ............................................................................................................................. 19
CONCLUSIONS ............................................................................................................................... 20
REFERENCES ................................................................................................................................. 21
APPENDIX A ................................................................................................................................... 23
Study 1 Experiment Description .......................................................................................... 24
APPENDIX B .................................................................................................................................... 25
Informed Consent Form ........................................................................................................ 26
APPENDIX C .................................................................................................................................... 27
Study 2 Experiment Description .......................................................................................... 28
APPENDIX D ................................................................................................................................... 29
Study 2 Questionnaire .......................................................................................................... 30
nl
LIST OF ILLUSTRATIONS
Figure
1.
2.
3.
4.
5.
6.
7.
8.
,
Title Page
Identification schematic .............................................................................................. 3
Placement schematic ................................................................................................. 3
Cumulative placement time within trials as a function of presentation media ....... 5
Identification time as a function of run number ........................................................... 7
Placement time as a function of run number .............................................................. 8
Total task time as a function of run number .............................................................. 9
Mean score as a function of luminous surfaces (LS's) in the visual field ................. 14
Mean score as a function of ambient illuminator (AI), LS's in the visual field,
and gender (G) ........................................................................................................... 14
Mean score as a function of AI, background visual complexity (BVC), and G ........ 15
iv
LIST OF TABLES
Table
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
Title Page
Analysis of variance (ANOVA) summary table for total task times ........................ 4
ANOVA summary table for identification times ......................................................... 4
ANOVA summary table for placement times ............................................................. 5
Placement time as a function of presentation media ................................................... 5
ANOVA summary table for identification time ........................................................... 6
ANOVA summary table for placement time ................................................................ 6
ANOVA summary table for total task time ................................................................. 6
Identification time as a function of run number ............................................................ 7
Placement time as a function of run number ................................................................ 8
Total task time as a function of run number ................................................................. 8
Illumination values for experimental conditions .......................................................... 12
ANOVA summary table for mean scores .................................................................... 13
Mean score as a function of luminous surfaces ........................................................... 14
Mean score as a function of AI, LS, and G .................................................................. 14
Mean score as a function of AI, BVC, and G .............................................................. 15
ANOVA summary table for score ................................................................................ 16
Descriptive statistics for the questionnaire ................................................................. 16
Correlations among selected questions ....................................................................... 17
Correlations between perceived distractions and reported fatigue ........................... 17
Correlations between G and selected questions ......................................................... 18
Correlations between session mean scores and questionnaire responses ............... 18
V
TECHNICAL MEMORANDUM
ASSESSMENT OF A HEAD-MOUNTED MINIATURE MONITOR
INTRODUCTION
On Space Station Freedom (S.S. Freedom), there will be a need for a "portable workstation"to be used to access, among other things, electronically stored "owner's manuals" for in situ main-
tenance operations. Far too often, however, people tend to envision a "laptop" computer when they
think of this "portable workstation."
In orbit, though, a laptop has some distinct disadvantages due to the unique microgravity
environment. One disadvantage has to do with carrying the laptop to the work site. Holding it ties up
a hand that would have been used for grabbing handholds and mobility aids along the translationroute. Once the work site has been reached, another disadvantage becomes evident--the laptop
must be restrained in a secure manner, otherwise it will float away. This requires a restraint
assembly and a restraint attachment location on the surrounding structure. Ideally, these would
place the monitor within, or at least near, the crewmember's task-centered cone-of-vision.
Unfortunately, due to constrained work-site envelopes and limited numbers of restraint
attachment locations, the monitor would probably be located outside this cone-of-vision. Thus, the
crewmember would need to frequently turn his/her head to alternately view the task area and refer to
the procedures and schematics displayed on the monitor. This increases task time and, more
importantly, shakes the vestibular system. The latter often leads to "stomach awareness" and,
consequently, reduced productivity.
However, if one "wore" the portable workstation, many of these obstacles could be over-
come. There is clearly a need for modular, portable, "wearable" input and output devices. 1 One such
component would be a head-mounted display. This is not to be confused with a head-up display
(requiring a visor) nor a helmet-mounted display (requiring a helmet), but a miniature monitor that
can be worn on a lightweight headset. The "Private Eye" is such a device, and its evaluation is the
subject of this report.
The Private Eye is a miniature monitor that, when placed before the eye, creates a virtual
image equivalent to that seen on a 12-in monitor 2-ft away. The unit is 1.2 in (height) by 1.3 in
(diameter) by 3.5 in (width), weighs 2.25 oz, and requires 1/3 W of power. Resolution is 720horizontal by 280 vertical pixels with an image size of 21.8 ° horizontal by 14.2 ° vertical and refreshrate of 50 Hz.
Two studies were conducted to assess the Private Eye's capabilities and limitations. The
first examined the effects of different information presentation media (Private Eye, CRT, and hard
copy) and work envelope volume (constrained and unconstrained) on the performance of anidentification and manual assembly task. The second study, using the Private Eye as the
presentation media, examined the effects of ambient illumination, luminous surfaces in the field-of-
view, and background visual complexity on the performance of an interactive animated computertask.
EXPERIMENT 1
Method
Overview. Subjects performed an identification and manual assembly task using visually pre-
sented component and configuration schematics. The task required the subject to frequently alternateattention between the displayed information and the task. Both work envelope volume and method of
information presentation were manipulated.
_. The experimental design used in this study was a 2 by 3 by 2, full-factorial design
with two within-subjects variables and one blocking variable (gender). Two independent variables
were manipulated, the amount of physical space available to perform the task and the method bywhich the schematics were presented. The work envelope (WE) for the task had two levels: either
constrained (within a simulated 19-in rack) or not constrained (on a table top). The presentation
media (PM) for the graphical information had three levels: the Private Eye, a CRT monitor (RGB
Apple II monitor), or hard copy (black graphics on white background on 8.5- by 11-in sheets in
landscape orientation). The presentation order of the six conditions was counter-balanced using a
balanced latin square. Subjects were randomly assigned (without replacement) to one of the pre-
sentation sequences. Task and subtask times were collected as the dependent variables.
_tlTj.f..¢_. Twelve NASA engineers (six males and six females) participated in this study on a
voluntary basis.
Task. The task was to assemble the "Drive Ya Nuts" puzzle (Milton Bradley), consisting of
seven "nuts" that must be placed on seven pegs. Each nut must be properly oriented and placed on
the correct peg. Starting with the nuts upside-down, the subject would pick up and examine eachuntil the correct one was identified, based upon the schematic of a nut presented on the display.
Incorrect nuts were returned to the table upside-down. The display would then be advanced to the
next schematic, showing where and in what orientation that nut should be placed. The subject would
then place the nut accordingly. This continued until all seven nuts were in place. This task was
chosen because it required frequent reference tO the schematics to both identify the correct nut and
place the nut on the correct peg in the proper orientation.
Materials and Aooaratus. Six sets of schematics were developed for each of the presentation
media (Private Eye, CRT_ and hard copy). Each set consisted of seven pairs of identification
schematics (fig. 1) and placement schematics (fig. 2) corresponding to the seven nuts and theirassociated locations. Each set began with an identification schematic of a nut that was to be located
on one of the outer pegs, as indicated by the following placement schematic. The next two pairs ofschematics were for nuts located on the nonadjacent outer pegs. The next three pairs completed the
outer pegs with the seventh and final pair of schematics for the nut located in the center. Each set
began with a different outer peg resulting in six sets. Subjects used each set once during a session,
one for each experimental condition. The presentation order of the sets for each subject was counter-
balanced using a balanced Latin square.
A "Fome-cor" box, with the front and back open, provided a "deep window" (12-in height
by 9-in diameter by 19-in width) through which the subjects performed the task in the constrainedWE condition. The intent was to simulate a maintenance and/or assembly task that might take place
inside a 19-in wide rack (the rack size as currently baselined for S.S. Freedom).
4
5
Figure 1. Identification schematic. Figure 2. Placement schematic.
Procedure. Each subject would read a description of the experiment (appendix A), then read
and sign an informed consent form (appendix B). Then following an acclimation period on the Private
Eye and a short familiarization period on the puzzle, the experiment would begin. All six conditions
were subsequently presented. There was a short rest period between trials while the equipment
was reconfigured. The trial began as the subject "paged" to the first identification schematic. Theinitial identification subtask time began at this time and continued until the subject paged to the fin'st
placement schematic. The first placement subtask time then began and continued until the subject
paged to the next identification schematic. This process was continued until the puzzle was com-
pleted. Upon completion of the final condition, the subjects were thanked and debriefed.
Results
The subtask times for the identification and placement of each nut were summed for each trial
to give cumulative trial identification and placement task times. Analyses of variance were performedon these cumulative trial subtask times and on trial total task time. No significant main effects nor
interactions were found in either total task times or identification times (tables 1 and 2).
The analysis of variance of the cumulative trial subtask placement times (table 3) showed a
significant main effect of PM, F(2,20) = 3.557, p < 0.05.
A post hoc Newman-Keuls pair-wise comparison of the means was performed at the 5-per-cent level of significance. Placement times were statistically significantly faster with the CRT than
with the hard copy (table 4 and fig. 3), CDN_r (first diagonal) = 5.49, CDN-K (second diagonal) =
6.66. There were no other significant differences in this post hoc test.
A second set of analyses of variance was undertaken to ascertain whether or not there was
any practice and/or fatigue effects occurring during the six "runs" within a session. These analysesincluded the Run*Gender interaction. A main effect of Run was found for the identification (F*(5,50)
= 2.446, p < 0.05, table 4), placement (F(5,50) = 8.860, p < 0.001, table 5), and total task times
(F(5,50) = 5.578, p < 0.001, table 6).
3
Table 1. Analysis of variance (ANOVA) summary table for total task times.
Source df Sum o/Squares Mean Square F
Between SubjectsGender (G) 1 6.125 6.125 0.002
Subjects (_/G 10 32,917.361 3,291.736
_ithin SubiectsPresentation Media (PM) 2 356.778 178.389 0.352
PM*G 2 1,264.333 632.167 1.247
PM*_G 20 10,136.556 506.828Work Envelope (WE) 1 3,458.347 3,458.347 2.908
WE*G 1 572.347 572.347 0.481WE*_JG 10 11,894.139 1,189.414PM*WE 2 1,480.778 740.389 1.021
PM*WE*G 2 1,345.778 672.889 0.928PM*WE*_$./G 20 14,497.111 724.856
Total 71 77,929.653 11,973.487
t
Table 2. ANOVA summary table for identification times.
Source d/ Sum o/Squares Mean Square F
Between SubiectsGender (G) 1 171.125 171.125
Subjects (S.)/G 10 22,883.250 2,288.325
_ithin SubjectsPresentation Media (PM) 2 176.583 88.292
PM*G 2 1,383.083 691.542PM*_/G 20 7,179.333 358.967
Work Envelope (WE) 1 1,711.125 1,711.125WE*G 1 583.681 583.681
WE*_/G I0 5,249.028 524.903PM*WE 2 1,130.583 565.292
PM*WE*G 2 859.194 429.597PM*WE*_G 20 10,447_889 522.394
Total 71 51,774.874 7,935.243
0.075
0.2461.926
3.2601.112
1.0820.822
4
Table 3. ANOVA summary table for placement times.
Source df Sum of Squares Mean Square F
B¢twcen Subjects
Gender (G) 1 112.500 112.500
Subjects (_.)/G 10 2,837.611 283.761
Within Sub_iectsPresentation Media (PM) 2 591.361 295.681
PM*G 2 35.583 17.792
PM*_/G 20 1,662.389 83.119
Work Envelope (WE) 1 304.222 304.222WE*G 1 0.056 0.056
WE*,5./G 10 2,012.056 201.206PM*WE 2 25.861 12.931
PM*WE*G 2 93.861 46.931
PM*WE*S/G 20 1,870.944 93.547
0.396
3.557 *
0.214
1.512
0.000
0.138
0.502
Total
*p -- 0.048
71 9,546.444 1,451.746
Table 4. Placement time as a function of presentation media.
Presentation Media Mean (s)
CRT 30.25
Private Eye 32.49
Hard Copy 37.13
38.00 E
O35.00 --_ _"
32.00 _-.
29.00 _
0
3
Figure 3. Cumulative placement time within trials as a function of presentation media.
Table 5.
Source
ANOVA summary table for identification time.
df Sum of Squares Mean Square F
Between Subiects
Gender (G) 1 171.125 171.125Subjects (_)/G 10 22,883.250 2,288.325
3 01ia.Su.bi z Run (R) 5 5,262.792 1,052.558Run*G 5 1,937.458 387.492
Run *_G 50 2 I, 520.250 430.405
0.075
2.446 *0.900
71 51,774.875 4,329.9o5*p=0.o465
Table 6. ANOVA summary table for placement time.
Source df Sum of Squares Mean Square F
Between Subig¢ts
Gender (G) 1 112.500 112.500 0.396
Subjects (_/G 10 2,837.611 283.761
)£ilhia&lkit,Run _) 5 2,789.778 557.956 8.860Run*G 5 657.833 131.567 2.089
Run*_G 50 3,148.722 62.974
Total 71 9,546.444 1,148.758
*p = 0.0001 ,,
Table 7. ANOVA summary table for total task time.
Source df Sum of Squares Mean Square F
Between Subjects
Gender (13) 1 6.125 6.125
Subjects (._.)/G 10 32,917.361 3,291.736
Within SubjectsRun (R) 5 I5,191.236 3,038.247Run*G 5 2,578.792 515.758
Run*_G 50 27,236.139 544.723
0.002
5.578 *0.947
Total 71 77,929.653 7,396.589
*p = 0.0004
6
Table 8. Identification time as a function of run number.
Run Number Mean (s)
1 86.9
2 80.4
3 66.7
4 65.2
5 68.8
6 64.2
- 90.00
8o.oo70.0o
160.00
Figure 4. Identification time as a function of run number.
A post hoc Newman-Keuls pairwise comparison of the means was performed at the
5-percent level of significance for the main effect of Run for all three dependent variables.
There were five significantly different comparisons for placement times (CD,v_/c (f'_rst diago-
nal) = 6.517, CD]v_K (second diagonal) = 7.834, CD_v_K (third diagonal) = 8.625, CD_v_K (fourth
diagonal) = 9.186, and CD_v_K (fifth diagonal) = 9.609). Placement times for the first run were
significantly longer than for any of the five subsequent runs. No differences in placement time werefound among the latter five runs (table 9 and fig. 5).
There were five significantly different comparisons for the total task times (CDN_ K (first
diagonal) = 19.168, CDN_K (second diagonal) = 23.041, CD_e_K (third diagonal) = 25.365, CD_v_K
(fourth diagonal) = 27.016, and CDN_K (fifth diagonal) = 28.262). Total task times for the first run
were significantly longer than for any of the last four runs, but not significantly different from the
second run. The second run was significantly longer than the fifth run. No differences in total tasktime were found among the latter four runs (table 10 and fig. 6).
7
Table 9. Placement time as a function of run number.
Run Number Mean (s)
1 45.8
2 36.0
3 30.5
4 31.3
5 28.3
6 27.7
A
55.00
45.00 !
35.00 !25.00
Figure 5.
Table 10.
Placement time as a function of run number.
Total task time as a function of run number.
Run Number Mean (s)
1 132.7
2 116.4
3 97.24 96.5
5 97.2
6 91.9
120.00 _!-
Run 1
140.00
120.00
iiiiilillji oooo // ooo
Figure 6. Total task time as a function of run number.
No statistically significant differences were noted among the runs in identification times using
the Newman-Keuls test (CDmK (first diagonal) = 17.038, CDmt¢ (second diagonal) = 20.481, CDmK
(third diagonal) = 22.547, CDN-K (fourth diagonal) = 24.014, and CDmt¢ (fifth diagonal) = 25.122).
However, since the ANOVA F-ratio for this main effect was statistically significant, further
analysis was indicated to uncover the basis for this finding. Thus, a less conservative least signifi-
cant difference (LSD) test, still at the 5-percent level of significance, was performed. Four compar-
isons were significant using this test (CDt,so = 17.024). Identification times for the first run were
significantly longer than for any of the last four runs, but not significantly different from the secondrun. No differences in identification time were found among the latter five runs (table 8 and fig. 4).
Discussion
There were two related goals in the first experiment. The first was to determine if the Private
Eye was suitable for a task that required frequent reference to displayed information. That is, would
it compare favorably with more "standard" methods of information presentation (e.g., CRT and hard
copy)? The second goal was to compare the three media in a constrained work environment, one that
should clearly favor ready access to the necessary displayed information.
In terms of the first goal, the Private Eye compares quite favorably with both the CRT and
hard copy. No decrements in performance were evident with the Private Eye, vis-a-vis, the CRT and
hard copy. The only difference in this area was between the CRT and hard copy, which is more than
likely an artifact of the "paging" method (i.e., a keystroke for the CRT versus manually flipping a
page for the hard copy).
The second goal was not fully demonstrated. The task design, in all fairness, could not place
the CRT and hard copy so far away as to require the subject to physically move to access the infor-
mation. Adding transit time to the subtask times would have clearly biased the results in favor of the
Private Eye. The decision was made to place the CRT and hard copy in the optimal position in each
case. That is, as close as possible to the edge of the constrained work envelope. Initial considerationwould seem to indicate that when this is possible there is no clear advantage (or disadvantage) inusing the Private Eye. However, applications where it is possible to optimally position the monitoror hard copy may be infrequent, particularly if the application is similar to an in situ maintenancetask.
Another finding in this experiment relates to a training or practice effect. Placement timeswere longer in the first run than the following runs. Using a less conservative test, a similar trendwas found for identification times. Combined total task times also showed this improvement in per-formance. In general, improvement was evident following the first and, to some extent, the secondruns. By the third run, this improvement had leveled off. The most likely explanation for this finding isa practice effect, both with the task and the experiment. That is, the subject becomes better at thetask and more relaxed during the experiment. More practice is indicated in the former and may evenhelp to alleviate the latter.
As with all within-subject's experiments, one must anticipate carry-over effects from onecondition to another and design accordingly. In this experiment, a balanced Latin square wasemployed to counterbalance the sequences of condition presentation. With this technique, eachcondition precedes and follows every other condition an equal number of times, thus carry-overeffects and differential transfer effects are decoupled from the independent variables of interest.
Further consideration for applications within a microgravity environment argues well for useof the Private Eye. Even in the best case, where a standard-sized monitor or hard copy could beplaced at the edge of the constrained work envelope, the user would be required to frequently turnhis/her head to alternately view the task and the displayed information.
As noted above, this raises havoc within the otolith organs, causing the otoliths to "slosh"around inside the utricle and saccule, the organs that sense gravity and linear accelerations of thehead. 2 In a one-gravity environment, this is not a problem since gravity is an overwhelming accel-eration force, holding the otoliths rather stable. In orbit, however, one is in a continual free-fall, free
of the effects of Earth's gravity. There, head movements shake the otolith organs causing uncomfort-able sensations (e.g., stomach awareness, etc.).
The task design could not satisfactorily reproduce these effects of frequent head movement ina microgravity environment, hence the presumed superiority of the Private Eye in this applicationwas not adequately, empirically addressed. In theory, though, the Private Eye should prove superiorin this type of environment. A Spacelab flight test should be arranged to verify this empirically.
EXPERIMENT 2
Method
Overview. Subjects "played" an interactive video game using the Private Eye as a monitor.The task required close, focused attention on the monitor. Ambient illumination, background visualcomplexity, and luminous surfaces within the visual field were manipulated.
_. The experimental design used in this study was a 24, full-factorial design with three
within-subjects variables and one blocking variable (Gender). Three two-level independentvariables were manipulated: the amount of ambient illumination (AI) in the experiment room
10
(bright/dark), the degree of visual complexity (background visual complexity (BVC)) of the wall the
subject faced (simple/complex), and luminous surfaces (LS) within the subject's visual field
(present/absent). Presentation order of the eight conditions were counter-balanced using a balanced
Latin square. Subjects were randomly assigned (without placement) to one of the presentation
sequences. Game scores were recorded as the dependent variable.
_t_ig._. Sixteen NASA and contractor engineers (eight males and eight females) partici-
pated in this study on a voluntary basis.
Task. The task used in this study was "Space Invaders," an interactive, animated video
game. The objective of the game was to "shoot space invaders" with missiles from "rocket ships."
The invaders were arranged in a 5 by 9 matrix that slowly advanced towards the bottom of the
screen. The subject controlled the motion of the ship using the cursor movement keys and fh'ed
missiles using the space key. The invaders also fired missiles that could destroy the ship. The sub-
ject began with three ships in each game. A game ended when all three ships were destroyed. Each
subject played five games per condition. The dependent variable was the game score.
A task was needed that required constant, focused attention. In the "real world" application,
the user will be highly motivated to attend to the displayed information. In the laboratory environ-
ment, however, instructing a subject to be motivated does not necessarily result in a motivated sub-
ject. By choosing a simple game, it was assumed that the subjects were motivated by a sense of
competition and, therefore, focused their attention on the task. The interactive nature of the taskensured constant attention and further enhanced focused attention.
Materials and Apparatus. Subjects sat in an American Ergonomics' "Ergomax" chair at a
3-ft wide "computer" table with a keyboard located directly in front of them. The small experiment
room (4-ft wide by 10-ft long) was illuminated by an overhead, indirect fluorescent lighting system
for the bright ambient illumination conditions. This lighting system was turned off in the "dark"ambient illumination conditions.
Two sheets of "Fome-cor" provided the two BVC stimuli. One was painted flat black (4.3-
percent reflectance), providing a visually simple background. The other was white with 2-in wide
horizontal and vertical strips of black tape placed at 4-in centers across the surface, resulting in 2-in
white squares (85.8-percent reflectance) surrounded by 2-in wide horizontal and vertical black
stripes (3.0-percent reflectance). This provided the visually complex background with an overallreflectance of 44.4 percent. These sheets were placed, in turn, on top of and perpendicular to the
table top, 9 in from the front edge.
A Sunnex 700 series halogen task lamp was placed behind and to the right of the subject. Its
3,000 to 3,200 K light was directed onto the surface of the Private Eye assembly, to the right of the
display, to provide the luminous surface (i.e., glare) in the subject's visual field condition.
Illumination values were determined for the various lighting conditions. Placing the photome-
ter sensor adjacent to the right eye reference position (ERP), readings were taken with the sensor
pointing up, in (toward the BVC stimulus panels), and to the right side for each of the eight treat-ment conditions (table 11).
11
Table 11. Illumination values for experimental conditions.*
Luminous SurfacesAmbient Illumination
BackgroundVisual
Complexity
Complex
Simple
Direction
InSide
UpIn
Side
Bright
89.023.5
40.275.0
13.536.0
Glare
Dark
11.02.87.04.60.86.0
*All measurements are expressed in foot-candles (fc).
Bright
'86.5
21.0
33.0
67.512.7
30.O
No GlareDark
NegligibleNegfigibleNegligibleNegfigibleNegligibleNegligible
Procedure. Prior to the day of the test sessions, each subject participated in a practice
session. This was to both practice playing "Space Invaders" and to become familiar and comfortable
with the Private Eye. Subjective self-report was the end-of-practice criterion.
Prior to the test session, each subject would read a description of the experiment (appendix
C), then read and sign an informed consent form (appendix B). Then, following a short "warm-up"
and acclimation period on the task and the Private Eye, the experiment would begin. All eight condi-tions were subsequently presented. There was a short rest period between trials while the equip-
ment was reconfigured. Upon completion of the final condition, subjects completed a short question-
naire (appendix D), then were debriefed and thanked for their participation.
Results
The five game scores within each condition were averaged to give a mean score for each
subject for each condition. An analysis of variance was performed on these means scores (table 12).
This analysis showed a significant main effect of LS's within the visual field. Direct glare had a
statistically significant detrimental effect on performance, F (1,14) = 5.715, p < 0.05 (table 13 and
fig. 7).
There were two statistically significant interaction effects on performance, AI by LS by G,
F(1,14) = 9.700, p < 0.01 (table 8 and fig. 5), and AI by BVC by G, F(I,14) = 5.524,
p < 0.05 (table 15 and fig. 9).
A post hoc Newman-Keuls pair-wise comparison of the means was performed at the 5-per-
cent level of significance for each interaction. There were six significantly different comparisons in theAlby LS by G interaction (CDu_r (first diagonal) = 219.7, CDu_x (second diagonal) = 268.3, CDu_K
(third diagonal) = 298.0, CDu_K (fourth diagonal) = 319.7, CDu_K (fifth diagonal) = 336.4, CD_r_K
(sixth diagonal) = 350.2, and CDu-x (seventh diagonal) 361.8).
12
Table 12. ANOVA summary table for mean scores.
Source df Sum of Squares Mean Square F
Between Subie¢_s
Gender (G) 1 232,988.445 232,988.445
Subjects (_.)/G 14 11,997.665 856,976.048
Y£ialia_ ab.tce Ambient Illumination 1 13,633.133 13,633.133
(AI)AI*G 1 273.195 273.195
AI*_/G 14 2,012,216.297 143,729.735
Luminous Surfaces 1 1,567,556.445 1,567,556.445
(LS)LS* G 1 426, 541.570 426, 541.570
LS*_G 14 3,839,777.109 274,269.794
Background Visual 1 62,613.758 62,613.758Complexity (BVC)
BVC*G 1 4,429.658 4,429.758
BVC*_G 14 1,099,762.609 78,554.472
AI*LS 1 33,120.945 33,120.945
AI *LS *G 1 815,843.445 815,843.445
AI*LS*S/G 14 1,177,477.734 84,105.552
AI*BVC 1 183,542.258 183,542.258
AI*BVC*G 1 1,012,286.633 1,012,286.633
AI*BVC*S/G 14 2,565,496.234 183,249.731
LS*BVC 1 166,536.633 166,536.633
LS*BVC*G 1 116,825.695 116,825.695
LS*BVC*S/G 14 2,391,073.297 170,790.950
AI*LS*BVC 1 252,849.383 252,849.383
AI*LS *BVC*G 1 795,848.820 795,848.820
AI*LS*BVC*_/G 14 4,956,829.422 354,059.244
0.272
0.095
0.002
5.715 *
1.555
0.797
0.056
0.3949.700 t
1.002
5.524 _
0.975
0.684
0.714
2.248
Total 127 35,725,187.818 7,830,625.642
*p = 0.031
'p = 0.008
*p = 0.034
13
_ Table 13. Mean score as a function of luminous surfaces.
Luminous Surfaces Mean Score
No Glare 2,112.9
Glare 1,891.6
/ _2,200.002,100.00
/ m---------_ _ooo__
_ ,,_oooo|1,800.00
2
Figure 7. Mean score as a function of LS's in the visual field.
Table 14. Mean score as a function of AI, LS, and G.
Luminoous
Surfaces
No Glare
Glare
Ambient
111umination
Dark
Bright
Dark
Bright
Male
2,232.8
2,023.2
1,704.1
1,878.2
Gender
Female
2,045.9
2,149.8
2,067.5
1,916.4
- 2,200.00
.=
- 2,000.00 t_
1,600.00
No Glare G' "-" " '_lare Z Female
Dark Brig_ MaleuaJ_, Bright
Figure 8. Mean score as a function of AI, LS's in the visual field, and G.
14
Table 15. Mean score as a function of AI, BVC, and G.
Background
Visual Complexity
Ambient
Illumination
Gender
Male Female
Simple Dark 1,857.9 2,135.8
Bright 2,093.8 2,010.1H.,
Complex Dark 2,079.0 1,977.6
Bright 1,807.7 2,056.2
i__ _ 2,200.00
? ,,oo.oo
_ 1,700.00
_u Corffr_;'_,' I I Female
Dark Bri_ Male
Figure 9. Mean score as a function of AI, BVC, and G.
In the dark condition with glare, females scored more points than males. Without glare, in
both bright and dark conditions, males and females scored more points than did males in the darkcondition with glare. Finally, males scored more points in the dark without glare than they did in the
bright condition with glare.
No statistically significant differences were noted in the AI by BVC by G interaction using
the Newman-Keuls test (CD_v_r (first diagonal) = 324.3, CD_v_K (second diagonal) = 328.6, CD_,_K
(third diagonal) = 439.8, CDN-K (fourth diagonal) = 471.9, CDN4¢ (fifth diagonal) = 496.6, CD,v_K
(sixth diagonal) = 516.9, and CDN_K (seventh diagonal) = 534.0).
However, since the ANOVA F-ratio for this interaction was statistically significant, further
analysis was indicated to uncover the basis for this finding. Thus, a less conservative LSD test, still
in the 5-percent level of significance, was performed. One comparison was significant using this test
(CDtsD = 324.6). Females, in the dark with a simple visual background, scored more points than did
males in the bright ambient condition with a complex visual backgroufid.
A second set of analyses of variance was undertaken to ascertain whether or not there was
any practice and/or fatigue effects occurring during the five "games" within a trial and/or the eight"trials" within a session. These analyses included the Game*Gender and Trial*Gender interactions.
There were no statistically significant main effects nor interactions found in this analysis (table 16).
15
Table 16. ANOVA summary table for score.
Source df Sum of Squares Mean Square F
Between SubiectsGender (G) 1 1,208,014.814 1,208,014.814
Subjects ($.)/G 14 60,302,285.341 4,307,306.096
Within Sub iectsTrial (I') 7 7,285,353.027 1,040,704.718
T*G 7 7,158,430.281 1,022,632.897
T*_./G 98 103,221,844.223 1,053.284.125Game 4 5,73%800.056 1,434,450.014
Game*G 4 3,855,357.745 963,839.436Game*S/G 56 54,872,180.431 979,860.365
Residual 448 352,082,597.986 785,898.656
Total 639 595,723,863.904 12,796,051.121
Table 17. Descriptive statistics for the questionnaire.
Question Response*
0.280
0.9880.971
1.4640.984
Frequency of playing video games t
Ever played "Space Invaders"*
Adequacy of PE as compared to a CRT
Dominant eye
Difficulty in focusing on Private EyeLevel of comfort
Wear glasses/contacts
More comfortable light level
I
Yes = 7/No = 44
Left = 2/Right = 143
3
Yes = 7/No = 9
High -- 5/Low = 11
Distraction of direct task light
Distraction of background walls
Difficulty at blocking out distractions
Fatigue level at completion
Overall impression of the Private Eye
Adequate training period I
Current emotional/physical condition
4
32
3
4
Yes
4
*Rounded mean responses are 1 = low / 5 = high, except as noted
*0 = none / 5 = high
*No response from five subjects
tAll subjects responded yes
Responses to the questionnaire were reduced and coded. Questions 1 and 2 were combined
into one six-point question. The rest of the questions remained as written. Means or frequencies
were computed for these questions (table 17).
16
Correlation coefficients were computed among selected questions concerning adequacy of the
Private Eye as compared with a CRT, a subject's dominant eye, difficulty in focusing, level of com-
fort, and whether or not a subject wore glasses or contacts (table 18). Notable findings include a
relatively high correlation between perceived adequacy of the Private Eye (relative to a "normal
monitor") and reported level of comfort (R = 0.741, R 2 -- 0.548). Moderate correlations were found
between perceived adequacy of the Private Eye and a dominant right eye (R = 0.562, R 2 = 0.316),
reported level of comfort and a dominant right eye (R = 0.493, R 2 - 0.243), and reported level of
comfort and the use of glasses or contacts (R = 0.572, R 2 -- 0.327). Little or no correlation was found
between difficulty in focusing and perceived adequacy of the Private Eye (R = 0.081, R 2 = 0.007), a
dominant right eye (R = 0.249, R 2 = 0.062), level of comfort (R = 0.066, R 2 - 0.004), or use of
glasses or contacts (R = 0.143, R 2 = 0.021) and between perceived adequacy of the Private Eye and
the use of glasses or contacts (R = 0.372, R 2 = 0.138).
Table 18. Correlations among selected questions.*
PE vs. Dominant Difficulty in Level of Glasses/
Question CRT Eye Focusing Comfort Contacts
PE vs. CRT X 0.562/0.316 0.081/0.007 0.741/0.548 0.372/0.138
Dominant eye X 0.249/0.062 0.493/0.243 N/ADifficulty in focusing X 0.066/0.004 0.143/0.021Level of comfort X 0.572/0.327Glasses/contacts X
*RfR2
Correlations between perceived distractions and reported fatigue level at the completion of
the session were computed (table 19). Notably, there was little correlation between reported fatigue
and the perceived distractions of the task light (R = 0.160, R 2 = 0.026) or the background walls
(R = 0.129, R 2 = 0.017), but a relatively large correlation between reported fatigue and the reported
difficulty in blocking out distractions (R = 0.803, R 2 = 0.645).
Table 19. Correlations between perceived distractions and reported fatigue.*
Fatigue level
Question at completion
Distraction of direct task light
Distraction of background walls
Difficulty at blocking out distractions
0.160/0.026
0..129/0.0170.803/0.645
*R/R 2
There were few notable correlations between gender and selected questions (table 20). Low
to moderate correlations were found between being female and perceived adequacy of the PrivateEye (R = 0.557, R 2 = 0.310), level of comfort (R = 0.365, R 2 -- 0.134), and positive emotional and/or
physical condition (R = 0.354, R 2 = 0.126). Little or no correlation was found between gender andfrequency of playing video games (R = 0.113, R 2 = 0.013), difficulty in focusing (R = 0.180,
R 2 = 0.032), distraction of direct task light (R = 0.146, R 2 = 0.021) or background walls (R = 0.095,
R 2 = 0.009), difficulty at blocking out distractions (R = 0.103, R 2 = 0.011), fatigue level (R = 0.194,
R 2 = 0.038), or overall impression of the Private Eye (R = 0.222, R 2 = 0.049).
17
Table 20. Correlationsbetweengenderand selectedquestions.*
Question Gender
Frequency of playing video games
Adequacy of PE as compared to a CRT
Difficulty in focusing on Private EyeLevel of comfort
Distraction of direct task light
Distraction of background walls
Difficulty at blocking out distractions
Fatigue level at completion
Overall impression of the Private Eye
Current emotional/physical condition
0.113/0.013
0.557/0.310
0.180/0.032
0.365/0.134
0.146/0.021
0.095/0.009
0.103/0.011
0.194/0.038
0.222/0.049
0.354/0.126
*R/R _
Finally, correlations between the session mean score and the questionnaire responses were
computed (table 21). Low to moderate correlations were found between session mean scores and
frequency of playing video games (R = 0.445, R 2 = 0.198), a dominant right eye (R = 0.419,R 2 = 0.176), and difficulty in focusing (R = 0.465, R 2 = 0.216). Little or no correlation was found
between session mean scores and having ever played "Space Invaders" (R = 0.224, R 2 = 0.050),
perceived adequacy of the Private Eye (R = 0.059, R 2 = 0,003), level of comfort (R = 0.076,R 2 = 0.006), the use of glasses or contacts (R = 0.108, R 2 = 0.012), comfort of different ambient lightlevels (R = 0.121, R 2 = 0.015), distraction of direct task light (R = 0.309, R 2 = 0.095) or background
walls (R = 0.003, R 2 = 0.8E-6), difficulty at blocking out distractions (R = 0.011, R 2 = 0.1E--4),
fatigue level (R = 0.022, R 2 = 0.5E-4), overall impression of the Private Eye (R = 0.129, R 2 = 0.017),
or emotional and/or physical condition (R = 0.068, R 2 = 0.005).
Table 21. Correlations between session mean scores and questionnaire responses.*
Question
Session MeanScore
Frequency of playing video gamesEver played "Space Invaders" CY = 1, N = 2)Adequacy of PE as compared to a CRT
Dominant eye (L = 1, R = 2)Difficulty in focusing on Private EyeLevel of comfort
Wear glasses/contacts (Y = 1, N = 2)
More comfortable light level (Bright = 1, Dark = 2)Distraction of direct task light
Distraction of background wallsDifficulty at blocking out distractions'
Fatigue level at completionOverall impression of the Private Eye
Current emotional/physical condition
0.445/0.1980.224/0.050
0.059/0.0030.419/0.176
0.465/0.2160.076/0.006
0.108/0.0120.121/0.015
0.309/0.0950.00318E-6
0.01 l/IE-40.022/5E-4
0.129/0.0170.068/0.005
*R/R2
18
Discussion
The goal of the second experiment was to determine the effects of various local visual
parameters on the ability of the user to accurately perceive the information on the Private Eye. If the
ability to read the monitor was adversely affected by the level of ambient illumination or degree of
background visual complexity, then its usefulness in the field would be limited. Regardless of howwell the monitor can be read in controlled "office" env_onment, if it cannot be reliably read under the
various conditions that might be found in situ, then its usefulness onboard the S.S. Freedom, is
limited. Regardless of its low weight and power requirements, its small volume, and most
importantly, its capacity to be worn on the head, if it cannot be reliably read under the various condi-
tions that might be found in situ, then its usefulness onboard the S.S. Freedom is limited.
Based on the results of this second study, it would appear that the Private Eye is capable of
being utilized under a variety of local visual conditions. No significant differences in operator per-
formance were evident between bright and dark ambient illumination. Neither did a complex visual
background have a detrimental effect on performance. There were also no differences based on thevarious combinations of these factors.
Luminous surfaces within the field-of-view did have a negative effect on performance. Under
certain conditions, direct glare, reflected from the light-colored bezel surrounding the monitor,
reduced the contrast ratio to the point where perceiving the contents of the display was significantly
impaired. This effect was particularly pronounced for males in an otherwise dark environment.
Admittedly, it took a deliberate effort on the part of the experimenter to align a point source of light
to reflect off the bezel into the subject's eye and a cooperative subject not to adjust the monitor
and/or head to avoid the glare. Thus, this does not appear to be a major drawback in considering the
Private Eye for use in situ. However, it is a relatively easily remedied human factors concern thatshould be addressed.
A more concerted effort was made in the second experiment to adequateIy train the subjects
before starting the experiment. This effort was apparently successful, as there were no significantly
different scores among games within a trial or among trials within the session. In addition, all sub-
jects indicated on the postsession questionnaire that they had received an adequate training period.
Questionnaire responses indicate a favorable judgment of the Private Eye in comparison to a
"normal monitor" and a favorable overall impression of the Private Eye. In terms of subjective
responses to the independent variables, subjects found the glare highly distractive. This is supported
by the objective experiment data which showed a significant performance decrement with glare.
Visually complex backgrounds were reported to be only moderately distractive. This, again, is
supported by the experimental data which showed no differences in performance between the visu-
ally simple and complex task backgrounds. More subjects found the dark condition more comfortable
(11 to 5), but no performance differences were evident in the experiment data.
Only two relatively high correlations stand out. The judged adequacy of the Private Eyevis-a-vis "normal monitors" and reported level of comfort are correlated, with over half of the
variation of each "explained" by the other. This suggests that further improvements in comfort
might enhance the perceived adequacy of the Private Eye.
The second relatively high correlation concerns distractions and fatigue. Neither glare nor
visually complex backgrounds correlated with reported fatigue, but difficulty in blocking out distrac-
tions did. Almost two-thirds of the variation of reported fatigue is "explained" by difficulty in
blocking out distractions (and vice versa). Although not directly related to the Private Eye, this
19
suggeststhat increasing distraction tolerance (through training, desensitization, etc.) might reduce
fatigue and, thus, improve productivity. This insight might be particularly beneficial for thoseenvironments that have distractions that cannot be further reduced.
CONCLUSIONS
Two studies were conducted to assess the Private Eye's capabilities and limitations. The
first examined the effects of different information presentation media (Private Eye, CRT, and hard
copy) and work envelope volume (constrained and unconstrained) on the performance of an identifi-
cation and manual assembly task. The second study, using the Private Eye as the presentationmedia, examined the effects of ambient illumination, luminous surfaces in the field-of-view, and
background visual complexity on the performance of an interactive animated computer task.
The first study demonstrated that the Private Eye compared favorably with both a CRT and
hard copy for a task that required frequent reference to displayed information. In this study, the CRT
and hard copy were placed in a near-optimal location relative to the _sk. In a work environment
where a "normal" monitor or hard copy can be near-optimally located, there appears to be no
expected performance benefit, nor loss, in choosing among the three presentation media. As thework environment becomes constrained, at least in the manner employed in this study, the use of
hard copy becomes a burden. As the work environment becomes more constrained, or for that matter
dynamic, both hard copy and "normal" monitors would become burdens. It is under these conditions,
in particular, that the Private Eye can enhance performance.
The second study demonstrated that the Private Eye is capable of being utilized under avariety of local visual conditions. Bright or dark ambient illumination environments and/or visually
simple or complex task backgrounds had no effects on performance. Direct glare off the bezel sur-
rounding the monitor did degrade performance, but this appears to be a monitor housing design
problem that can be easily overcome.
Taken together, these studies indicate that the Private Eye is an effective means of present-
ing information, comparable to "normal" monitors and hard copy, and can be utilized in a variety ofambient illumination conditions and task visual environments. Thus, the Private Eye seems well
suited for in situ operations that require ready reference to information.
This is especially true in a microgravity environment where having both hands free for trans-
lation and restraint is desirable, and restraint locations for hard copy or monitors are few and far
between. In addition, the latter would not necessarily be located in the crewmember's task-centeredfield-of-view. Thus, the crewmember would need to frequently turn his/her head to alternately view
the task area and refer to the procedures and schematics displayed on the monitor. This increases
task time and, more importantly, shakes the vestibular system. The latter often leading to "stomach
awareness" and, consequently, reduced productivity.
In summary, there is a need for a head-mounted display to support onboard in situ opera-
tions. It must be comparable to "normal" monitors and/or hard copy, in terms of information display,
and readable in a variety of ambient illumination conditions and task visual environments. The
Private Eye appears to satisfy these requirements.
20
REFERENCES
1. National Aeronautics and Space Administration: "Proceedings of the Workshop on Technology
for the Space Station Evolution." Washington, DC, 1990.
2. Howard, I.P.: "The Vestibular System." In "Handbook of Perception and Human Performance,"
K.R. Boff, L. Kaufman, and J.P. Thomas (eds.), Wiley, New York, 1986, pp. 11-1-11-30.
21
APPENDIX A
Study 1
Experiment Description
_L___. INTENT]ONAL_.Y,3L_Nt PRECEDinG PAGE BLAN_ NOT FILMED
23
STUDY 1 EXPERIMENT DESCRIPTION
EXPERIMENT OVERVIEW
The purpose of this experiment is to examine performance on an an assemblytask using three kinds of presentation media under two conditions. In this experiment,you will be asked to assemble the Drive Ya Nuts puzzle. Following a familiarizationand practice period, six data collection trials will begin. The data collected during yourattempts will be treated with anonymity.
The three presentation media are: the "Private Eye, a miniature monitor; a cathoderay tube (CRT); and hard copy. There will be two trials for each of the presentationmedia. Half of these will be performed within a confined work envelope and half willbe performed in an unobstructed work envelope. Thus, a total of six assemblysequences will be attempted under these two conditions. The assembly sequence willchange for every trial.
The experimenters will request that you wear a miniature monitor mounted on aheadset as one form Of presentation media. You should not experience any eye strainor difficulty if you follow the procedures outlined in the detailed description of theexperiment.
The entire experiment is expected to last no longer than I hour.The research team consists of:
1. Julie Cosper, Industrial Engineer Co-op, Man-SystemsIntegration Branch, 544-2806.
2. Frankie Rice, Industrial Engineer Co-op, Man-SystemsIntegration Branch, 544-2806.
3. Joe Hale, Man-Systems Integration Branch, 544-2193.The research is sponsored by NASA, Marshall Space Right Center, Huntsville,Alabama.
Further instructions will follow your reading and signing the attached informedconsent form. These instructions will then provide more detail on the assemblyprocedures and any additional information you will need. As the informed consentform indicates, you have the right to decline to participate at any point in theexperiment. This includes declining to participate after reading the additionalinstructions. Participation is voluntary.
A member of the experimental team will answer any questions you may have.However, in cases that may affect the outcome of the experiment, the team membermay delay a detailed answer until you have completed the experiment.
You are requested to refrain from discussing the experiment with other individualswho may be come subjects. We expect all data to be taken by April 13, 19g0.Following that date, feel free to discuss the experiment with anyone you wish.
Finally, we want to point out that the assembly task is not difficult. The experimentis not designed to test your skill. We are only interested in how your performance mayvary based on the different trial conditions. Furthermore, as indicated earlier, the datawill be treated with anonymity.
24
APPENDIX B
Informed Consent Form
25
INFORMED CONSENT FORM
PARTICIPANT'S CONSENT
As a participant in this experiment, you have certain rights. The purpose ofthis form is to make you aware of these rights and to obtain your consent toparticipate. Your participation is voluntary.
1. You have the right to stop the experiment in which you are participatingat any time if you feel that it is not agreeable to you.
. You have the right to see your data and to withdraw it from theexperiment, if you feel that you should. In general, data are processedafter all runs are completed. In this experiment, we can provide you withsome qualitative information immediately after the experiment.Subsequently, all data are treated with anonymity. Therefore, if you wishto withdraw your data, you must do so immediately after yourparticipation is completed.
. You have the right to be informed on the results of the overallexperiment. If you wish to receive information on the results, pleaseinclude your address with your signature below. A summary will be sentto you.
We hope you will find the experiment a pleasant and interesting experience.The research team involved greatly appreciates your help as a participant. Ifyou have any questions about the experiment or your rights as a participant,please do not hesitate to ask. We will do our best to answer them, subject onlyto the constraint that we do not want to pre-bias the experimental results.
Your signature below indicates that you have read the above stated rightsand that you consent to participation. If you include your printed name andaddress below, a summary of the experimental results will be sent to you.
Signature
Print name and address if you wish toreceive a summary of theexperimental results.
Witness' Signature
26
APPENDIX C
Study 2
Experiment Description
27
STUDY 2 EXPERIMENT DESCRIPTION
EXPERIMENT OVERVIEW
The purpose of this experiment is to examine performance onan interactive, animation task under a variety of conditions. In thisexperiment, you will be asked to "play" Space Invaders. Followinga few warm-up practice games, eight data collection trials willbegin. The data collected during your trials will be treated withanonymity.
Three parameters (each with two levels) will be manipulatedduring this experiment with all possible combinations presented.These are" Ambient Illumination (High/Low), LuminousSurfaces in the field-of-view (Yes/No), and Background VisualComplexity (Simple/Complex). There will be a short rest periodafter each trial, during which the experimenter will reconfigure thelights and background for the next trial. Upon completion of thelast trial, you will be asked to complete a short questionnaire. Theentire experiment is expected to last approximately 90 minutes.
The research team consists of:1. Gina Klinzak, New Technologies, Inc., 461-6464.2. Joe Hale, Man-Systems Integration Branch, 544-2193.
The research is sponsored by NASA, Marshall Space FlightCenter, Huntsville, Alabama.
Attached for you to read and sign is an informed consent form.This informs you that you have the right to decline to participate atany point in the experiment. Participation is voluntary.
A member of the experimental team will answer any questionsyou may have. However, in cases that may affect the Outcome ofthe experiment, the team member may delay a detailed answeruntil you have completed the experiment. You are requested torefrain from discussing the experiment with other studyparticipants until after their experiment session, as this mayinfluence their performance in some manner.
Finally, we want to point out that the task is not difficult. Theexperiment is not designed to test your skill. We are onlyinterested in how your performance may vary based on thedifferent trial conditions. Furthermore, as indicated earlier, thedata will be treated with anonymity.
28
APPENDIX D
Study 2 Questionnaire
29
STUDY 2 QUESTIONNAIRE
SubjectNumber:
Private Eye Test Questionnaireyes no
1. Do you play video games?
If no, skip to question 4.
2. How often do you play? i t I I I
Daily 4-5 times 1-2 times Once Occasionallyper week per week per month (every few
months)
, Have you every played Space Invadersbefore your training session?
yes no
. How would you judge your visual perception of the screen in comparison to anormal monitor?
i I 1 I II I I I
Highly Borderline Decidedlyadequate inadequate
5. Which would you judge to be your dominant eye? left dght
. What was your level of difficulty in focusing on the screen?
! I I
High Moderate Low
, What would you determine to be your level of comfort?
I ! I I I
High Moderate Low
3O
SubjectNumber:
Private Eye Test Questionnaire Continued.......yes no
8. Do you wear glasses/contacts?
, Which light level was more comfortable to you?
High Ambient Low AmbientIllumination Illumination
10. How would you judge the direct task light as a distraction?
I I I t I
No Little Moderate High SeverelyDistraction Distraction Distractive
11. How would you judge the background walls as a distraction?
I I I I I
No Little Moderate High SeverelyDistraction Distraction Distractive
12. How much difficulty did you have in blocking out distractions?
I I I I II I I I I
v--1No Little Moderately High Severely
Difficulty Diff'cult Difficult
13. How would you judge your fatigue level when finished?
I I I I I
No Moderate HighlyFatigue Fatigued
3]
Subject Number:.
Personal Observation
What was your overall impression of the Private Eye? [---! Strongly Like
D Like
!_1 Neutral
[_] Don't Like
[_ Strongly Dislike
Do you feel you had an adequate training period? I"-]yes
How do you feel today (eg. emotional/physical)?
no
!---] Excellent
I_1 Good
!"-1 Only Fair
[_ Poor
!"7 Terrible
Do you have any comments or suggestions regarding the Private Eye (eg. dataentry, screen display clarity, display layout)?
32
APPROVAL
ASSESSMENT OF A HEAD-MOUNTED MINIATURE MONITOR
By J.P. Hale II
The information in this report has been reviewed for technical content. Review of any
information concerning Department of Defense or nuclear energy activities or programs has been
made by the MSFC Security Classification Officer. This report, in its entirety, has been determinedto be unclassified.
_DiSecGRI,_ssi0n Operations Laboratory
"_ U.S. GOVERNMENT PRINTING OFFICE 1992-631.O60/60136
33
